#2: The "Provide struct/functions for handling TLSv1.3 key shares" commit breaks
server side for non-libressl clients, including if 1.3 is disabled. ssl alert,
decode_error. This is nasty for servers on -current.
This is a known issue related to Hello Retry Requests - I have code
ready to address it, however it still needs finialising and review.
In the interim I've disabled the TLSv1.3 client and we'll re-enable
it once the currently known issues have been addressed.